This penguin is lucky enough to be able to see his white feathers again after being caught in the slick of New Zealand's worst-ever environmental disaster but many more will not be so fortunate as the crisis deepens.

This bird was cleaned up at the wildlife centre in Tauranga where up to 350 more tonnes of oil has been spilled from the 'Rena' tanker, which lies stricken off the coast.

But clumps of heavy oil from the Liberia-flagged Rena have washed up on pristine beaches near Tauranga in the North Island, and environmental officials said 53 birds were found dead and 17 were getting emergency treatment to remove oil from their feathers.

I'm all white: A rescued oil-coated penguin recuperates at a wildlife centre in Tauranga last month

Before and after: Left, the rescued penguin gets a thorough scrubbing after being plucked from the oily waters, and right, he shows off his two-tone feathers once again

'This event has come to a scale where it is New Zealand's most significant environmental maritime disaster,' Environment Minister Nick Smith told reporters in Tauranga, adding that the clean-up would take weeks.

Rough conditions: Heavy seas and misty weather surround the cargo ship Rena that is stuck on the Astrolabe Reef, about 14miles from Tauranga

The ship has been sinking since it
ran aground last Wednesday on the Astrolabe Reef, about 14 miles from Tauranga Harbour, and the New Zealand government has
demanded to know why the ship crashed into the well-charted reef in calm
weather.

The ship owner has given no reason for the grounding, but says it is cooperating with authorities.
Rough weather in recent days has kept salvage crews away.

On Monday night, the 775ft
(236metre) ship shifted significantly, spilling hundreds of tons of oil
from an unidentified rupture in the hull, said Nick Bohm, a spokesman
for Maritime New Zealand which is managing the emergency response.

Pollution: A man walks past fuel oil that washed up on beaches at Papamoa, near Tauranga

Clean-up: Volunteers take an oiled little blue penguin out of the pool after the recovering session at the wildlife facility in Tauranga

Up to 390tons (350 metric tons) of
heavy fuel oil spilled from the hull on Tuesday, a rate about five times
worse than during the initial days of the spill, Smith said.

Bohm said a salvage crew had to be removed from the ship late on Tuesday
morning because ocean swells of 7-to-10ft (2-to-3metres) made
conditions too dangerous.

The swells were expected to increase as high as 16ft (5metres), he said.

Without the salvage crew aboard, oil cannot be pumped out of the ship.

'We're on standby at the moment and
we'll see what's happening with the ship and they'll be redeployed as
quickly as possible,' Bohm said of the salvage crew.

Environmental protectors: A crew disposes of oil washed ashore from the stricken ship

Volunteers help the clean-up operation. Plans to extract the oil from the vessel itself have been abandoned for the time being as the weather is expected to be terrible

'We're not saying it's going to break up yet; we're not convinced,' he added, referring to the ship.

Divers are scheduled to inspect damage to the hull on Wednesday, Bohm said.

Maritime New Zealand said in a
statement that a beach clean-up began early Tuesday and that more teams
would be deployed on Wednesday when oil is expected to reach the shore
in greater quantities.

'A significant amount of oil is expected to come ashore in the next days,' the statement said.

Rescue teams were also searching the shore for more wildlife affected by the oil.

Marine crews began an operation on
Sunday to extract up to 1,900 tons (1,700 metric tons) of heavy fuel oil
from the stricken ship - the equivalent of about 10,700 barrels.

But they had to halt the pumping Monday after managing to remove just 11 tons (10 metric tons).

In a statement, the owners of the
ship, Greece-based Costamare said they were 'cooperating fully
with local authorities' and were making every effort to 'control and
minimise the environmental consequences of this incident'.

The company did not offer any explanation for the grounding.

Globules of thick, black
oil washed up on the beach showed yesterday that it's a race against time in order to save New
Zealand's stunning coastline.

Fist-sized clumps of oil were found
at Mount Maunganui beach, a favourite spot for surfers, according to
Maritime New Zealand, the agency responsible for shipping in the region.

The beach is about 100miles south-east of Auckland.

Because Rena a cargo ship rather than
an oil tanker, any spill would be small in comparison to disasters like
the 1989 Exxon Valdez disaster, which dumped an estimated 262,000
barrels of oil in Alaska's Prince William Sound.

But because the ship is close to
shore, the oil could still foul delicate estuaries in an area known for
its pristine environment.

The operation is expected to last at least two more days once it resumes.

Clean-up: A shag covered in oil is helped by vets at a wildlife rehabilitation facility shortly after a ship spilled 400tons of fuel, killing more than 2,000 sea birds, last month

Devastation to wildlife: Environmental officials said 53 birds were found dead and 17 were getting emergency treatment to remove oil from their feathers

About 200 people are working on the operation, and New Zealand's defence force has about 300 people standing by in case major beach clean-ups are needed.

New Zealand Prime Minister John Key visited the area on Monday and demanded answers.

'This is a ship that's ploughed into a well documented reef in calm waters in the middle of the night at 17 knots, so somebody needs to tell us why that's happened,' he said.

The Rena was built in 1990 and was carrying 1,351 containers of goods when it ran aground, according to the owners.

In addition to the oil, authorities are also concerned about some potentially dangerous goods aboard, including four containers of ferro-silicon.

Authorities said they would make it a priority to remove those goods as part of their operation.